In recent years, more and more emphasis has been placed on the use of insulation in dwellings to conserve energy and reduce noise. At the same time, architectural designs have created a multitude of different designs and styles which do not always lend themselves to the use of more classic fiberglass or other fibrous batts (often paperbacked and sold in rolls) of uniform factory created widths, and as such, do not fully fill the space in which the batting is installed. This, in turn, has created a need for a technique of applying fiberglass (or other fibrous) insulation which does not use batts of factory determined dimensions.
While others have heretofore fulfilled this need to a limited extent by developing various blown-in-place insulation techniques, this need was truly met, quite successfully, by the loose-fill, blown-in-place system and technique disclosed in U.S. Pat. Nos. 5,641,368 and 5,666,780, and commercially employed under the trademark ULTRAFIT DS.TM. by Guardian Fiberglass, Inc. In this patented ULTRAFIT DS.TM. technique and system, loose-fill fiberglass (or cellulose fiber) and a water activated adhesive is admixed with water as it is being blown into, for example, the space between wall, ceiling or floor studs of a residential home or other dwelling. The fast setting adhesive quickly bonds the fibers in an adhering mat to the stud area, regardless of the area's size or shape, thus effectively achieving a uniform volume of insulation which completely fills the desired area for energy conservation, as well as sound insulation purposes, regardless of its shape or size.
While this ULTRAFIT DS.TM. system and other known blown-in-place techniques overcame the above-described drawback of incomplete fill inherent in batt/rolls of insulation, one of the advantages of a factory manufactured batt is the ability to maintain quality control at the factory level. This includes, of course, the density and thickness of the product, so important to the achievement of a uniform R-value. Density of fibrous insulation as well as thickness, are, in this respect, well recognized as being directly related to the "R-value" of the insulation. Thus, as is well known, when factory made batt insulation is purchased, for example, to place in a new residential home, it is often purchased by specifying its "R-value" and, due to its factory determined dimensions, can be counted on at the job site using minimal prescribed installing techniques to achieve the required R-value, often specified on the package or backing of the batt itself.
When, on the other hand, a "blown-in-place" technique is employed, this "factory" controlled R-value advantage is lost and thus it is often necessary to also employ with it a technique at the job site for measuring density for assuring that the in-situ mat as formed has the requisite density and thickness, and thus the specified or desired R-value. Since the thickness is generally achievable with smoothing and testing with a needle gauge probe, ease and accuracy of determining density, with reasonable accuracy, becomes the governing factor at the job site in achieving the required R-value (often per contractual obligation).
Heretofore various techniques have been employed to test for density of in situ formed, blown-in-place insulation. For example, in certain known techniques the open wall cavity is first filled with blown-in-place insulation, such as fiberglass or cellulose. Then, a hand held scoop of known volume and weight is used to scoop out some of the insulation that has been blown into the cavity. The scoop, including the scooped out insulation, is then weighed in order to determine the density of the insulation that has been blown into the cavity. By knowing the volume and empty weight of the scoop, and then reweighing the scoop filled with insulation, it is possible to determine the density (wt./vol.) of the insulation that was blown into the cavity. R-value is then determined for the as installed insulation in a known fashion by knowing the thickness of the layer from which the insulation was scooped and by the installer using a chart which has, through testing, pre-correlated thickness and density to R-value. The sample taken, however, is small, may be compressed in the scoop, or may not fully fill the scoop. On this small a scale, moreover, error can be magnified if care is not taken to perform the scooping correctly, or a number of scoops are performed for averaging.
In a somewhat similar technique which seeks to predetermine density prior to actually filling the space to be insulated, a 5 oz. (148 ml) Dixie cup is filled from the blower gun. The cup is tapped gently as it is being filled to remove all air pockets. By knowing the weight of the cup itself and thereafter weighing the filled cup, the density (wt./vol.) is calculated. Again, a chart or other guideline correlating density and thickness to R-value is employed to determine the R-value achieved when the insulation is thereafter blown into its intended final location. Once again, of course, the use of such a small cup can give rise to the potential for resulting inaccuracy in the final product, or multiple testing and averaging must be done to overcome this potential error factor.
In yet another technique known to be used, for example, in Great Britain, a portable wooden closed, but openable, box (e.g. 21".times.21".times.4") is filled through a small opening in the box by a pressure nozzle which blows insulation into the box until it is shut off by a predetermined back pressure thereby, hopefully, indicating that the box is completely "filled". By knowing the weight of the empty box, its volume and the weight of the presumably "filled" closed box, the density of the insulation therein may be estimated by calculation. As can be seen, the box is closed when filled, is not in place in the wall cavity itself when filled, and its "filled" condition is determined by back pressure (unless opened and inspected, and redone if found not filled). Because the box is not hung in the wall cavity which is filled simultaneously therewith, the test does not necessarily replicate an "in place" wall cavity fill which actually occurs when the wall cavity is eventually filled. The technique is thus subject to inaccuracy, and the need for possible multiple testing if upon opening the box it is found that the box has not filled properly when the back pressure shuts off nozzle flow.
In view of the above, it is apparent that there exists a need in the art for an improved method and corresponding apparatus for installing insulation that is blown into open wall cavities to a prescribed density wherein the improved method and apparatus provide increased accuracy.